Spatial distribution patterns of demersal and epibenthic communities on the Galician continental shelf (NW Spain)

Spatial distribution patterns of epibenthic communities on the Galician continental shelf were studied using multivariate methods. Data came from 5 surveys carried out in 2002, 2003 and 2004. Beam trawls and otter trawls were used to study epibenthic communities along 8 transects perpendicular to the coastline. The role of depth, season, latitude and sediment characteristics was examined. Seven habitats were described according to bathymetry and sediment characteristics. There were weak linear relationships between environmental variables and species richness, biomass and species diversity. However, the canonical analysis showed that depth and sediment characteristics greatly influence smaller epibenthic communities sampled by beam trawl. Six assemblages were obtained for beam trawls: inner shelf mud, very fine sands, and fine sands, middle shelf sands, and outer shelf very fine sands, and fine sands. Five assemblages were identified for larger-sized and swimming epibenthos sampled with otter trawls. These assemblages were also determined according to depth and sediment type but sediment characteristics were less important. Otter trawl assemblages were the same as the beam trawl ones, except for on the outer shelf where no differences between sediment type were detected. For both gears, inner and outer shelf assemblages displayed a higher biotic variability than the middle shelf, as a consequence of a higher environmental heterogeneity. Typifying species were mainly eurytopic in the middle shelf, whereas eurytopic and stenotopic species characterised the inner and outer shelves.     

60Si2Mn钢制六角螺母冲头强韧化热处理的研究

用光学显微镜,硬度计和透射电子显微镜研究了淬火加热温度,回火温度和回火时问对60Si2Mn 钢的显微组织、硬度和亚结构的影响;对60Si2Mn 钢制六角螺母冲头进行了寿命试验;采用模拟理想冷却曲线设计的方便易行、节能省时的强韧化热处理,可显著提高冲头的使用寿命.     

船舶柴油机推进系统硅油减振器参数匹配优化

本文对23000DWT散货船推进轴系进行响应振动计算,将理论计算与实船测试值对分析,验证了振动模型、算法和MATLAB程序的正确性。借助模糊层次分析法对所构建的硅油减振器匹配优化评价体系进行计算与分析,得到最合理的硅油减振器类型；同时根据已验证的轴系离散数学模型和MATLAB程序对匹配后的轴系进行计算分析,结果表明匹配后硅油减振器使轴系振动应力降低10%左右,为降低船舶推进轴系振动研究提供理论指导意义。     

"以胶代垫"平面密封技术的研究及在汽车上的应用

阐述了耐油硅酮密封胶及涂胶机的研制开发技术,并通过一系列试验证明了“以胶代垫”工艺的先进性和可行 性。该技术已成功应用于汽车生产且具有良好的推广前景。     

硅粉和沸石粉双掺配制高强度大流动性混凝土

在采用普通：水泥、碎石、天然砂和高效减水剂等常规原材料配制的混凝土中,通过复合掺加硅粉和沸石粉材料．可以配制出高强度、大流动性的混凝土,并在超高层建筑和大跨度结构等方面具有十分广阔的应用前景。     

弹性体灯桩在航标系统的应用及前景

介绍随着新材料和新技术的进步,应用于航标系统的一种弹性体材料的灯桩,并简述其应用前景。弹性体材料灯桩的主要特征是便于施工和维护。     

室内空气质量控制:新世纪的挑战和暖通空调人的责任

  目的  为保障舰员健康与舰船的安全运行,应对以挥发性有机化合物（VOC）为代表的舱内空气污染物进行有效控制。污染物的释放速率是表征舱室空气质量的关键参数之一,但目前在该方面的研究还较为欠缺。  方法  基于常规室内环境污染速率测试方法,结合舰船舱室特点,通过Tenax-TA采样管富集采样、ATD-GC/MS分析和集总参数模型拟合,对舱室内以苯、甲苯、乙苯和二甲苯（BTEX）为代表的VOC释放速率进行研究。选取某舰船典型舱室为研究对象,开展封舱与通风工况下BTEX的释放速率测量试验。  结果  结果表明：通风工况下,该舱室二甲苯和挥发性有机化合物总量（TVOC）的平衡浓度均超出了室内空气质量标准,应加强污染源头控制或改善通风净化效能;封舱工况下（舱室环境浓度与通风工况接近）,除浓度较低的苯以外,BTEX的释放速率与通风工况下的测试结果吻合较好。  结论  该研究初步建立了适用于舰船舱室的VOC释放速率测量方法,可为其污染特征评估与通风净化系统设计提供参考。     

4H-SiC MOSFET静态温度特性的仿真分析

SiC材料具有较大的禁带宽度、高临界电场、高载流子饱和漂移速度和高热导率等优良特性,能广泛应用在高温、高压、大功率等领域。为探究温度对4H-SiC MOSFET静态特性的影响规律,以指导高温高压环境下4H-SiC MOSFET的设计与制造,文章基于Silvaco平台对高压4H-SiC MOSFET器件进行了仿真建模,获得了其不同温度下的击穿电压、转移特性和输出特性,探究了温度对其击穿电压、阈值电压、饱和漏电流、导通电阻的影响规律。文章最终得到了300 K时击穿电压为4450 V的SiC MOSFET器件元胞结构模型,验证了其静态特性及参数受温度影响较明显,该影响规律符合SiC MOSFET的静态特性理论。     

Summer hypoxia adjacent to the Changjiang Estuary

Changjiang, the third largest runoff in the world, empties into the East China Sea from Shanghai, the fastest developing area of China. With the increasing nutrient load from the river, a severe hypoxia zone was found to about 2  10⁴ km². The mechanism of hypoxia formation adjacent to the Changjiang Estuary receives more and more attention from both scientists and managers. This paper discusses the relationship between hypoxia and the water masses, primary production, particulate material transport and the density stratification in these areas according to data obtained from a cruise in September, 2003. Hypoxia is formed by organic detritus decay. The particulate organisms do not mainly come from the Changjiang river, or from the dead algal deposed locally, but from the local benthic algae or particles advected from the south. Maintenance of hypoxia is due to the large density stratification caused by the significant salinity difference between the fresh plume and salty water from Taiwan Strait. This applies also to other estuaries with large runoff and rapid economic growth drainage, such as the Pearl River. It is suggested that the hypoxic zone here is much more sensitive than that outside Mississippi River. More cruises over different weather and tide conditions are needed to prove this hypothesis. Interdisciplinary research should be further developed in the future.